What is it?

This board lets you connect your RetroShields to Teensy 3.5 and add super-powers to your 8bit microprocessor :)

• Uses Teensy 3.5 (sold separately here)
• much faster (120Mhz ARM vs 16Mhz ATMega)
• more memory (256 KB vs 6K)
• micro SDCard connector
• Same simple development tools (use existing Arduino IDE programming environment with fast compilation)
• 6502 and 6809 can now run at 1.0Mhz clock speeds.

This board also supports NGT30 Video/Keyboard Shield. I like NGT30 because it is possible to make your own stand-alone computer :)

What do you get?

Two options:

• PCB w/ SMT parts soldered.
• Kit: PCB + connectors

NOTE: This price is much better. First, cost is cheaper with a larger quantity build in China. Second, I took out the tall headers from the kit that are needed for Arduino shields. These tall connectors are expensive and I am assuming not everybody will use them. If you want them, please send me an email.

Why did you make it?

Teensy is faster and more capable platform than Arduino, however I had two issues w/ existing Teensy adapter boards:

First was voltage level mismatch. Teensy 3.5 is advertised as 5V-tolerant. What it really means is its inputs are 5V-tolerant. It still outputs 3.3V signals. For most 5V devices, 3.3V is high enough to register logic-high but some microprocessors wanted higher voltages. These did not work reliably or not work at all. Hence I needed true 3.3V <-> 5.0V level shifting.

Second, we read 16bits of address bus and read/write 8bits of data bus to/from the processors. Existing teensy adapters required reading one bit at a time due to random gpios and bit shift/or/and operations wasted cpu cycles. I reassigned the Teensy gpio's to the arduino mega header so simple 8-bit register read/write's can be used.